1. Field of the Invention
The present invention relates to a network service information providing system and network service information providing apparatus and method and terminal thereof. More particularly, it relates to a network service information providing scheme which efficiently informs the user of a system required by the user and provides information needed for the user to construct a new wireless system and provide service, in an environment where various wireless communications service coexist.
2. Description of the Prior Art
By network type, networks are classified into infrastructure networks where a trunk network managed by an operator has various functions for cutting off communications with terminals used by users, and ad hoc networks (networks formed temporarily of mobile terminals alone without any relay node) where users gather together and terminals communicate with each other directly. In terms of radio used as a transmission medium of a network, there are various schemes including a wireless cellular scheme which has a relatively low transmission rate, but covers a wide area and wireless LAN scheme which has a high transmission rate, but covers a small area.
Systems which employ the wireless LAN scheme can be used as infrastructure networks which connect to the Internet with wireless base stations (access points) installed at stations, airports, and other places where people gather together (hot spots), by taking advantage of its high transmission capacity. The wireless cellular scheme is widely used today for a portable telephone system, which covers a wide area throughout the country and is used as an infrastructure network, allowing communications to be conducted anywhere independent of location.
On the other hand, it is also possible to set up a so-called ad hoc network by interconnecting not only equipment around the user, but also the user's terminal and another user's terminal located nearby using short-range radio system, as typified by “Bluetooth,” which covers a range of 10 meters or less and is intended to interconnect equipment around the user, such as a portable telephone terminal and portable computer.
Such wireless systems can coexist with each other as shown in FIG. 17. A summary report (http://www.joho.soumu.go.jp/policyreports/joho_tsusin/bunk akai/abstract.pdf) by the New Generation Mobile Committee of the Special Interest Group on Information and Communications Technology of the Ministry of Public Management, Home Affairs, Posts and Telecommunications recommends that optimal wireless systems should be used according to specific needs of users. In FIG. 17, reference numeral 100 denotes the Internet, 101 denotes a cell of a cellular system, 102-1 and 102-2 denote cells of a wireless LAN system, and 103-1 and 103-2 denote ad hoc network cells.
The Internet 100, which serves as an infrastructure for the cell 101 of the cellular system and the cells 102-1 and 102-2 of the wireless LAN system, provide interconnection for them. Although only one cell 101 of the cellular system is shown in the figure for the sake of simplicity, there exist a plurality of adjacent cells with the cellular system covering a wide area.
The cells 102-1 and 102-2 of the wireless LAN system are connected to the Internet 100 and provide high-speed Internet connection services to hot spots crowded with users. The cells 102-1 and 102-2 of the wireless LAN system may be managed by different administrations because cells can be set up without permission using, for example, a wireless LAN in the 2.4-GHz ISM (Industrial Scientific Medical) band.
On the other hand, the ad hoc networks 103-1 and 103-2 form closed local networks without being connected to the Internet 100, which is an infrastructure. In these circumstances, a user who wants to access the Internet 100 can do so
(1) via a wireless LAN system if he/she can connect to the cell 102-1 or 102-2 of the wireless LAN system, or
(2) via a cellular system if he/she is out of reach to the cells 102-1 and 102-2 of the wireless LAN system.
Also, a user who wants to communicate with another user close by without connecting to an infrastructure such as the Internet can newly construct the ad hoc network 103-1 or 103-2.
If the ad hoc networks 103-1 and 103-2, the cell 101 of the cellular system which is an infrastructure network, and the cells 102-1 and 102-2 of the wireless LAN system coexist, control methods for connecting to an appropriate network or constructing an ad hoc network with consideration given to connectability to various networks and needs of users are available to allow users to connect to both the ad hoc networks and infrastructure network, connect to a desired network, or construct a new ad hoc network.
In a network environment in which various wireless systems coexist as shown in FIG. 17, possible services available to users include:
1) low-speed, but wide-area Internet access via a cellular system,
2) high-speed Internet access via a wireless LAN although limited to hot spots,
3) participation in local communications services provided by existing ad hoc networks, and
4) construction of a new ad hoc network and commencement of local communications services.
Regarding service 1), since cellular systems have a wide service area, users can receive the service regardless of their location. Regarding services 2) and 3), since service areas themselves are small, the users who want to receive service must move to the appropriate service area. In doing that, if the users know the service areas of services 2) and 3), they can move easily. However, services 2) to 4) have the following problems.
As for service 2), since changes occur in radio wave propagation characteristics as well as in the service area along with new construction or disuse of wireless LAN base stations or changes in building or structure layouts, it is difficult for users to keep updated. As to service 3), since the service is local, it is not possible to tell the duration and location of an ad hoc network in advance. Consequently, users cannot obtain information about the ad hoc network in advance and can only participate in it by chance. In the case of service 4), when constructing a new ad hoc network, it may interfere with any existing network around it, resulting in degradation of overall throughput.
Regarding providers which provide hot spot services using a wireless LAN, since there is no licensing system concerning the ISM band, different providers can provide hot spot services independently. Thus, there is high flexibility in providing services. However, existence of hot spots set up haphazardly may cause interference among them, resulting in significant degradation of throughput provided to the user.
An object of the present invention is to provide a network service information providing system and network service information providing apparatus and method and terminal therefor which allow users to readily know a location and radio transmission parameters for connecting to a narrow-area wireless communications system in a system which contains a mixture of wide-area wireless communications systems and narrow-area wireless communications systems and to set up a new narrow-area wireless communications system which can provide higher communications services without causing degradation in existing communications services in the environment where different wireless communications systems coexist.